Recently, the specifications for High Speed Packed Access (HSPA) have included Discontinuous Transmission (DTX) and Discontinuous Reception (DRX) in the context of the Continuous Packet Connectivity (CPC) functionality, see the standards third generation partnership project (3GPP) TS 25.308 “High Speed Downlink Packet Access (HSDPA); Overall description; Stage 2”. Rel-7, version 7.2.0 and 3GPP TR 25.903 Continuous Packet Connectivity (CPC) for Packet Data Users, Release 7. The deployment of DTX and DRX in HSPA is motivated by i.a. power saving and reduction of the Uu instantaneous interference. The Uu interface provides interconnection between the Radio Network Controller (RNC) and User Terminal via the Node B.
Furthermore, on Medium Access Control (MAC) level, the DRX functionality as described in the standard TS 25.308 can be used for frame bundling. The result of the inclusion of DRX on the MAC level is that:                The DTX functions are active as a pre-condition        The User Equipment (UE) is forced to buffer certain quantity of Radio Link Control (RLC) Protocol Data Units (PDUs) which are expected to be received in regular time intervals        The PDUs are deployed in big size transport formats in few Transmission Time intervals (TTIs)        Transmission is stopped when buffering, and        Retransmissions are allowed at any time.        
The Enhanced Uplink (EUL) DRX works by restricting the start of Enhanced-Dedicated Channel (E-DCH) transmissions to a cycle pattern. The cycle pattern is called MAC_DTX_cycle and the beginning of the cycle coincides with the beginning of the UE_DTX_cycle—1 specified to support the DTX functionality. The values of these cycles are signaled to the UE using a Radio Resource Control Protocol (RRC).
The transmissions are restricted when it has passed a configurable number of TTIs called UE_Inactivity_Threshold where the UE have not had a transmission (for example, because its buffer is empty). Then the UE does not transmit again until a new MAC_DTX_cycle starts. The UE_Inactivy_Threshold is signaled to the UE by RRC. The values for the UE_Inactivy_Threshold allowed by TS 25.331 in Release 7 (10.3.6.34a) are in the range from 0 to 512.
In addition, to start the transmission a configurable offset is applied. The offset is called UE_DTX_DRX_Offset which is RRC signaled to the UE.so that new transmission can be performed after the offset has being applied to the time of the beginning of the cycle, if there is need for one.
If a UE has transmitted in one E-DCH Transmission Time Interval (TTI), then the UE is allowed to use subsequent TTIs for E-DCH transmission as long as its transmission is continued (re-started) within UE_Inactivity_Threshold TTIs. In other word the UE can transmit continuously without being interrupted by the DRX feature. But if the UE stops the transmissions by the same number of TTIs that is configured with the threshold value, then the UE can not transmit even when it has data in the buffer until the condition for transmitting is fulfill again.
If there is need for Hybrid Automatic Repeat Request (HARQ) retransmissions, those can be done in the correspondent HARQ process without being affected by the DRX model, independently of the value of the Inactivity threshold and the current UE activity. An exemplary transmission performed in accordance with the existing transmission protocol is illustrated in FIG. 1.
With the current DRX specified functionality, some frame bundling can be achieved with the correct tuning of the parameters: UE_Inactivity_threshold and MAC_DTX_CYCLE, especially with 2 ms TTI. But for 10 ms TTI the situation is more difficult, because the longer HARQ RTT and the longer delay between transmission can lead to data received in such a way that restrict the DRX cycles heavily.
Hence there exist a need for a transmission method for EUL DTX that provides a more efficient use of resources and also can achieve an improved transmission.